Synthesis gas comprising carbon monoxide and hydrogen (hereafter syngas) is commonly produced by the partial oxidation (POX) of a hydrocarbon-containing fuel (hereafter, the POX process). The POX process is a highly exothermic process and produces a syngas stream at temperatures typically in range of 2100 to 2800° F.
A key challenge in the POX process, especially for carbon heavy fuels, is the removal of the entrained solid carbon (hereafter soot) produced as an undesirable byproduct. In particular, the soot that is generated in the POX reactor will tend to foul conventionally designed heat exchangers that are used to recover a portion of the heat from the exothermically generated syngas stream. Although special boilers have been developed to process soot-containing syngas, these designs cannot be readily transferred to heat exchange reforming wherein a portion of the heat is recovered from the POX generated syngas stream and used as at least a portion of the heat to facilitate the additional production of syngas via the (endothermic) catalytic reforming of natural gas and steam. Thus a system which can remove soot from syngas at high temperature offers a key advantage to the practice of heat exchange reforming.
Typically, the soot is removed by quenching and scrubbing the syngas with water. See for example EPO 648 828 B1 and WO 00/29323, both assigned to Texaco Development Corporation.
Alternatively, JP 50040117 teaches directly filtering the syngas through a carbonaceous material that traps the soot for a sufficient time period such that the oxygen containing molecules that are also produced as byproduct in the POX process [i.e. CO2 and H2O] are given an opportunity to react with, and gasify, the soot. After such in-situ gasification of the soot, JP '117 introduces the syngas (or “reducing gas” as referred to therein) into a blast furnace.
A concern with the in-situ gasification scheme as taught in JP '117 is the use of a carbonaceous material as the material for trapping the soot and subsequently allowing it to be gasified by reaction with the byproduct CO2 and/or H2O. In particular, the carbonaceous material will be susceptible to the very same gasification reactions that the carbonaceous soot is intended to undergo (i.e. via reaction against the byproduct CO2 and/or H2O). Consequently, a carbonaceous material will require more frequent replacing than a non-carbonaceous material.
The present invention addresses this concern by using a non-carbonaceous material to trap the soot.